Composting of rumen content waste using anaerobic-anoxic-oxic (A²2/O) system

Rumen content waste is generally dried and dumped into municipal landfill by the slaughterhouse (SH) in Indonesia. A composting process using anaerobic-anoxic-oxic (A² /O) method was selected for treating the SH solid waste for its advantage in nitrogen removal. The objectives of this study were to investigate optimum each composting duration, and effect of dolomite addition for alkalinity control. Six standing reactors of 60 L capacity were used in this experinment. Fifty kg of rumen content was placed in each reactor. The A² /O configuration periods of 25-10-15, 15-10-25, and 30-10-10 days were applied in this research. The composting process was conducted for 50 days. Aerobic condition was maintained using aeration rate of 0.5 L (kg-¹ dry weight solid waste) min-1 . Anoxic condition was established by 60 minute aeration rate of 0.28 L (kg-¹ dry weight solid waste) min-1 . The composting process was conducted for 50 days. This research showed that the optimum anaerobic-anoxic-oxic time period for composting the rumen content waste was 25-10-15 days. In this reactor, the moisture content was decreased from 83% to 72%. Temperature range was 29-34° C, pH values slighty fluctuated from 7.57 to 8.70. Inorganic nitrogen concentration decreased from 0.29 to 0.07%, and organic nitrogen concentration decreased from 2.04 to 1.19%. Dolomite addition did not give (P value>α, α = 0.05). This research proved that A A²O method is appropriate for treating solid waste with high nutrient contents.